The present disclosure relates to processes for the handling of toner particles. In particular, the present disclosure relates to expanding the function of downstream toner additives to improve cycle time in toner particle handling processes.
In the manufacture of chemical toners, washing is a processing step whereby toner particles are de-watered and washed to meet final quality specifications including, moisture content and removal of residual surfactants and ions. In an exemplary washing process, filter press plates are pressed down tightly against an interweaving filtration cloth creating one or more chambers configured to receive a slurry comprising toner particles. The slurry is fed into the chambers creating a wet filter-cake on the filter cloth while allowing liquids to flow through as a filtrate.
Dynamic washing can also be performed inside the same filter press, by passing wash liquid through the retained particles and then the filter cloth for additional washing as needed. Air drying is then typically performed on the washed cake to meet a desired moisture specification. The dried toner particles can be further processed to manufacture toner compositions comprising toner additives which are typically blended with the toner particles. These additives are designed to provide the toner composition with various properties such as flow control, overall charge, and other desirable characteristics of the toner.
The desirability of using smaller toner particles is it increases the image quality, reduces the amount of toner needed, and can provide potential cost savings in materials. However, one challenge that arises with the use of smaller toner particles is that the filtration cloth may be prone to blinding. Furthermore, smaller toner particles can cause increased cycle times for both filtration and dynamic washing. These effects are due to smaller toner particles decreasing cake porosity and hindering the path of liquids through the toner particle filter cake and filter cloth ultimately reducing washing efficiency and increasing cycle time.